MP28372
Dual 1.5A, 23V, 1.4MHz
Step-Down Converter
The Future of Analog IC Technology
DESCRIPTION
The MP28372 is a dual monolithic step-down
switch mode converter with built-in internal
power MOSFETs. It achieves 1.5A continuous
output current for each output over a wide input
supply range with excellent load and line
regulation.
Current mode operation provides fast transient
response and eases loop stabilization.
Fault condition protection includes cycle-by-cycle
current limiting and thermal shutdown. In
shutdown mode, the regulator draws 40μA of
supply current.
The MP28372 requires a minimum number of
readily available standard external components.
FEATURES
•
•
•
•
•
•
•
•
•
•
•
•
•
•
1.5A Current for Each Output
0.18Ω Internal Power MOSFET Switches
Stable with Low ESR Output Ceramic
Capacitors
Up to 90% Efficiency
40μA Shutdown Mode
Fixed 1.4MHz Frequency
Thermal Shutdown
Cycle-by-Cycle Over Current Protection
Wide 4.75V to 23V Operating Input Range
Each Output Adjustable from 0.92V to 16V
Configurable for Single Output with Double
the Current
Programmable Under Voltage Lockout
Programmable Soft-Start
Available in TSSOP20 with Exposed Pad
and SOIC Packages
Distributed Power Systems
I/O and Core supplies
DSL Modems
Set top boxes
Cable Modems
EVALUATION BOARD REFERENCE
Board Number
EV28372DF-01A
Dimensions
2.2”X x 1.6”Y x 0.4”Z
APPLICATIONS
•
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“MPS” and “The Future of Analog IC Technology” are Trademarks of Monolithic
Power Systems, Inc.
TYPICAL APPLICATION
12V
3.3V @ 1.5A
1
2
3
SSA
NC1
BSA
INA
SWA
PGA
SGA
FBB
COMPB
ENB
ENA
COMPA
FBA
SGB
20
19
18
17
16
15
14
13
10nF
12
11
Efficiency vs
Load Current
OFF ON
82pF
2A
Schottky
2.2nF
100
90
EFFICIENCY (%)
80
70
60
50
V
OUT
=3.3V
V
OUT
=5V
10nF
2A
Schottky
4
5
6
7
8
9
MP28372
PGB
SWB
INB
NC2
BSB
SSB
2.5V @ 1.5A
V
OUT
=2.5V
OFF ON
10
3.3nF
0
0.5
1.0
LOAD CURRENT (A)
1.5
MP28372 Rev. 1.4
12/10/2007
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2007 MPS. All Rights Reserved.
1
TM
MP28372 — DUAL 1.5A, 23V, 1.4MHz STEP-DOWN CONVERTER
PACKAGE REFERENCE
TOP VIEW
TOP VIEW
SSA
NC1
BSA
INA
SWA
PGA
SGA
FBB
COMPB
ENB
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
ENA
COMPA
FBA
SGB
PGB
SWB
INB
NC2
BSB
SSB
SSA
BSA
INA
SWA
GNDA
FBB
COMPB
ENB
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
ENA
COMPA
FBA
GNDB
SWB
INB
BSB
SSB
EXPOSED PAD
FOR TSSOP20F ONLY
Part Number*
MP28372DF
*
Package
TSSOP20F
Temperature
–40°C to +85°C
Part Number*
MP28372DS
*
Package
SOIC16
Temperature
–40°C to +85°C
For Tape & Reel, add suffix –Z (eg. MP28372DF–Z)
For Lead Free, add suffix –LF (eg. MP28372DF–LF–Z)
For Tape & Reel, add suffix –Z (eg. MP28372DS–Z)
For Lead Free, add suffix –LF (eg. MP28372DS–LF–Z)
ABSOLUTE MAXIMUM RATINGS
(1)
Supply Voltage (
INA, INB
)................................ 25V
Switch Voltage (
SWA, SWB
) .............................. 26V
Bootstrap Voltage (
BSA, BSB
) .................. V
SW
+ 6V
Feedback Voltage (
FBA, FBB
) ............–0.3V to +6V
Enable/UVLO Voltage (
ENA, ENB
)......–0.3V to +6V
Comp Voltage (
COMPA, COMPB
)...........–0.3V to +6V
Soft Start Voltage (
SSA, SSB
).............–0.3V to +6V
Junction Temperature .............................+150°C
Lead Temperature ..................................+260°C
Storage Temperature.............. –65°C to +150°C
Recommended Operating Conditions
(2)
Supply Voltage (V
IN
) ...................... 4.75V to 23V
Operating Temperature.................–40°C to +85°C
Thermal Resistance
(3)
TSSOP20F ............................. 40 ....... 6....
°C/W
SOIC16.................................. 105 ..... 40...
°C/W
Notes:
1) Exceeding these ratings may damage the device.
2) The device is not guaranteed to function outside of its
operating conditions.
3) Measured on approximately 1” square of 1 oz copper.
θ
JA
θ
JC
MP28372 Rev. 1.4
12/10/2007
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2007 MPS. All Rights Reserved.
2
TM
MP28372 — DUAL 1.5A, 23V, 1.4MHz STEP-DOWN CONVERTER
ELECTRICAL CHARACTERISTICS
V
IN
= 12V, T
A
= +25°C, unless otherwise noted.
Parameter
Feedback Voltage
Symbol Condition
V
FB
4.75V
≤
V
IN
≤
23V
Min
0.901
Typ
0.920
0.18
10
V
EN
= 0V, V
SW
= 0V
2.5
3.0
1.95
400
ΔI
C
=
±10
μA
V
FB
= 0V
630
930
1.4
210
9
I
CC
> 100μA
V
EN
Rising
0.7
2.37
1.0
1.0
2.50
210
V
EN
≤
0.4V
V
EN
≥
3V
V
FB
= 0.8V
t
ON
40
2.4
160
70
100
70
2.8
1.3
2.62
1230
10
Max
0.939
Units
V
Ω
Ω
µA
A
A/V
V/V
μA/V
MHz
KHz
kΩ
V
μA
V
mV
μA
mA
°C
%
ns
Upper Switch-On Resistance R
DS(ON)1
Lower Switch-On Resistance R
DS(ON)2
Upper Switch Leakage
Current Limit
(4)
Current Limit Gain
Output Current to Comp Pin
G
CS
Voltage
Error Amplifier Voltage Gain
A
VEA
Error Amplifier
G
EA
Transconductance
Oscillator Frequency
f
OSC
Short Circuit Frequency
f
SC
Soft-Start Pin Equivalent
Output Resistance
EN Shutdown Threshold
V
EN
Voltage
Enable Pull-Up Current
I
EN
EN UVLO Threshold Rising
V
UVLO
EN UVLO Threshold
Hysteresis
Supply Current (Shutdown)
Supply Current (Quiescent)
Thermal Shutdown
Maximum Duty Cycle
Minimum On Time
I
OFF
I
ON
D
MAX
Note:
4) Equivalent output current = 1.5A
≥
50% Duty Cycle
2.0A
≤
50% Duty Cycle
Assumes ripple current = 30% of load current.
Slope compensation changes current limit above 40% duty cycle.
MP28372 Rev. 1.4
12/10/2007
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2007 MPS. All Rights Reserved.
3
TM
MP28372 — DUAL 1.5A, 23V, 1.4MHz STEP-DOWN CONVERTER
PIN FUNCTIONS (TSSOP20F)
Pin #
1
2
3
4
5
6
Name
SSA
Description
Soft-Start Control for Channel A. 9kΩ output resistance from the pin. Set RC time constant
with external capacitor for soft start ramp time. Ramp Time = 2.2 x 9kΩ x C.
NC
No Connect
BSA
High-Side Driver Boost Pin. Connect a 10nF capacitor from this pin to SWA.
Supply Voltage Channel A. The MP28372 operates from a +4.75V to +23V unregulated input.
INA
Input Ceramic Capacitors should be close to this pin.
SWA
Switch Channel A. This connects the inductor to either INA through M1A or to PGA through M2A.
Power Ground Channel A. This is the Power Ground Connection to the input capacitor
PGA
ground.
Signal Ground Channel A. This pin is the signal ground reference for the regulated output
voltage. For this reason care must be taken in its layout. This node should be placed outside
SGA
of the D1 to C1 ground path to prevent switching current spikes from inducing voltage noise
into the part.
Feedback Voltage for Channel B. This pin is the feedback voltage. The output voltage is ratio scaled
FBB
through a voltage divider, and the center point of the divider is connected to this pin. The voltage is
compared to the on board 0.92V reference.
Compensation Channel B. This is the output of the transconductance error amplifier. A series
COMPB RC is placed on this pin for proper control loop compensation. Please refer to more in the
datasheet.
Enable/UVLO Channel B. A voltage greater than 2.62V enables operation. Leave ENB
unconnected for automatic startup. An Under Voltage Lockout (UVLO) function can be
ENB
implemented by the addition of a resistor divider from V
IN
to GND. For complete low current
shutdown the ENB pin voltage needs to be less than 700mV.
Soft-Start Control for Channel B. 9kΩ output resistance from the pin. Set RC time constant
SSB
with external capacitor for soft start ramp time. Ramp Time = 2.2x9kΩxC.
BSB
High-Side Driver Boost Pin. Connect a 10nF capacitor from this pin to SWB.
NC
No Connect.
Supply Voltage Channel B. The MP28372 operates from a +4.75V to +23V unregulated input.
INB
Input Ceramic Capacitors should be close to this pin.
SWB
Switch Channel B. This connects the inductor to either INB through M1B or to PGB through M2B.
Power Ground Channel B. This is the Power Ground Connection to the input capacitor
PGB
ground.
Signal Ground Channel B. This pin is the signal ground reference for the regulated output
voltage. For this reason care must be taken in its layout. This node should be placed outside
SGB
of the D1 to C1 ground path to prevent switching current spikes from inducing voltage noise
into the part.
Feedback Voltage for Channel A. This pin is the feedback voltage. The output voltage is ratio scaled
FBA
through a voltage divider, and the center point of the divider is connected to this pin. The voltage is
compared to the on board 0.92V reference.
Compensation Channel A. This is the output of the transconductance error amplifier. A series
COMPA RC is placed on this pin for proper control loop compensation. Please refer to more in the
datasheet.
Enable/UVLO Channel A. A voltage greater than 2.62V enables operation. Leave ENA
unconnected for automatic startup. An Under Voltage Lockout (UVLO) function can be
ENA
implemented by the addition of a resistor divider from V
IN
to GND. For complete low current
shutdown the ENA pin voltage needs to be less than 700mV.
7
8
9
10
11
12
13
14
15
16
17
18
19
20
MP28372 Rev. 1.4
12/10/2007
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2007 MPS. All Rights Reserved.
4
TM
MP28372 — DUAL 1.5A, 23V, 1.4MHz STEP-DOWN CONVERTER
PIN FUNCTIONS (SOIC16)
Pin #
1
2
3
4
5
6
Name
SSA
Description
Soft-Start Control for Channel A. 9kΩ output resistance from the pin. Set RC time constant
with external capacitor for soft start ramp time. Ramp Time = 2.2 x 9kΩ x C.
BSA
High-Side Driver Boost Pin. Connect a 10nF capacitor from this pin to SWA.
Supply Voltage Channel A. The MP28372 operates from a +4.75V to +23V unregulated input.
INA
Input Ceramic Capacitors should be close to this pin.
SWA
Switch Channel A. This connects the inductor to either INA through M1A or to PGA through M2A.
GNDA Ground A.
Feedback Voltage for Channel B. This pin is the feedback voltage. The output voltage is ratio scaled
FBB
through a voltage divider, and the center point of the divider is connected to this pin. The voltage is
compared to the on board 0.92V reference.
Compensation Channel B. This is the output of the transconductance error amplifier. A series
COMPB RC is placed on this pin for proper control loop compensation. Please refer to more in the
datasheet.
Enable/UVLO Channel B. A voltage greater than 2.62V enables operation. Leave ENB
unconnected for automatic startup. An Under Voltage Lockout (UVLO) function can be
ENB
implemented by the addition of a resistor divider from V
IN
to GND. For complete low current
shutdown the ENB pin voltage needs to be less than 700mV.
Soft-Start Control for Channel B. 9kΩ output resistance from the pin. Set RC time constant
SSB
with external capacitor for soft start ramp time. Ramp Time = 2.2x9kΩxC.
BSB
High-Side Driver Boost Pin. Connect a 10nF capacitor from this pin to SWB.
Supply Voltage Channel B. The MP28372 operates from a +4.75V to +23V unregulated input.
INB
Input Ceramic Capacitors should be close to this pin.
SWB
Switch Channel B. This connects the inductor to either INB through M1B or to PGB through M2B.
GNDB Ground B.
Feedback Voltage for Channel A. This pin is the feedback voltage. The output voltage is ratio scaled
FBA
through a voltage divider, and the center point of the divider is connected to this pin. The voltage is
compared to the on board 0.92V reference.
Compensation Channel A. This is the output of the transconductance error amplifier. A series
COMPA RC is placed on this pin for proper control loop compensation. Please refer to more in the
datasheet.
Enable/UVLO Channel A. A voltage greater than 2.62V enables operation. Leave ENA
unconnected for automatic startup. An Under Voltage Lockout (UVLO) function can be
ENA
implemented by the addition of a resistor divider from V
IN
to GND. For complete low current
shutdown the ENA pin voltage needs to be less than 700mV.
7
8
9
10
11
12
13
14
15
16
MP28372 Rev. 1.4
12/10/2007
www.MonolithicPower.com
MPS Proprietary Information. Unauthorized Photocopy and Duplication Prohibited.
© 2007 MPS. All Rights Reserved.
5
